Validation of On-Orbit Methodology for the Assessment of Cardiac Function and Changes in the Circulating Volume Using Ultrasound and Braslet-M Occlusion Cuffs, SDTO 17011 U/R (Braslet) - 09.17.14

Science Objectives for EveryoneValidation of On-Orbit Methodology for the Assessment of Cardiac Function and Changes in the Circulating Volume Using Ultrasound and Braslet-M Occlusion Cuffs (Braslet) is Station Development Test Objective (SDTO) 17011 sponsored by National Aeronautics and Space Administration (NASA) and Russian Federal Space Agency (FSA). Braslet is testing the performance of occlusion cuffs in modifying fluid shifts that occur early during physiological transition into the space environment. Understanding the effects of this countermeasure on cardiovascular function will be useful for both medical operations and future research.

Science Results for Everyone

Exposure to weightlessness in space is no picnic: crew members often experience facial puffiness, nasal stuffiness, painful eye movement, dizziness, nausea, and blood rushing to their heads. Russian cosmonauts have used thigh compression cuffs, called the Braslet, in early flight to counter these unpleasant effects. Researchers test a modified Braslet device (Braslet-M) on ISS crew members which show that it is effective in keeping more blood in the legs and could diminish head fluid shift and resulting vision changes. It could also effectively treat medical emergencies such as fluid buildup in the lungs. Longer-term application and intermittent, ongoing use have not been studied, although many Russian cosmonauts have used it for longer periods with no reported complications.

The following content was provided by Valery V. Bogomolov, Ph.D., M.D., J. Michael Duncan, M.D., and is maintained in a database by the ISS Program Science Office.

The Validation of On-Orbit Methodology for the Assessment of Cardiac Function and Changes in the Circulating Volume Using Ultrasound and Braslet-M Occlusion Cuffs, SDTO 17011 (Braslet) will result in ultrasound methodology for the measurement of cardiovascular volume and function in microgravity.

Ultrasound is an advanced diagnostic tool typically operated by experienced technicians with results interpreted by specialized physicians. Recent advances in remote guidance techniques on the International Space Station (ISS) will allow diagnostic quality ultrasound exams using crewmember operators who have little or no ultrasound experience. Ongoing efforts are required to validate procedures that will allow complex, focused ultrasound exams on the ISS.

Braslet will also utilize the Russian Braslet-M device, a current Russian operational countermeasure which compresses the upper thigh to slow the venous return of blood from the legs to the heart. The overall cardiovascular effects of the Braslet-M device are not completely understood. This SDTO combines the use of Braslet-M devices as a means to acutely alter volume distribution while focused ultrasound measurement techniques are developed.

The successful development of this measurement technique will provide a means of measuring cardiovascular function which will be useful for both medical operations and future research. Methodologies and data will be created through this SDTO that will result in significant new capability and knowledge which will enhance areas of operational space medicine such as clinical management of volume shifts induced by altered gravity, clinical diagnostic ultrasound in space flight, and telemedicine.

Description
The Validation of On-Orbit Methodology for the Assessment of Cardiac Function and Changes in the Circulating Volume Using Ultrasound and Braslet-M Occlusion Cuffs, SDTO 17011 (Braslet) is a collaborative effort between the National Aeronautics and Space Administration (NASA) and Russian Federal Space Agency (FSA) for which each organization acts as a portion of the co-investigator team. The goal of this investigation is to establish a valid ultrasound methodology for assessing a number of aspects of central and peripheral hemodynamics and cardiovascular function, specifically in rapid changes in intravascular circulating volume. This SDTO will use Braslet-M occlusion cuffs, which are a Russian-made operational countermeasure already pre-calibrated and available onboard for each ISS crewmember.

Braslet will use multiple modes of ultrasound imaging and measurements, in combination with short-term application of Braslet-M occlusive cuffs and cardiopulmonary maneuvers (Valsalva, Mueller) to demonstrate and to evaluate the degree of changes in the circulating volume on orbit. This will be accomplished by performing echocardiographic examinations in multiple modes (including Tissue Doppler mode), ultrasound measurements of lower extremity venous and arterial vascular responses to Braslet-M device under nominal conditions and also during cardiopulmonary Mueller and Valsalva maneuvers. Identical measurements will be repeated without Braslet-M, with Braslet-M applied, and immediately after releasing the occlusion device.

In addition to the primary goal of methodology validation for cardiovascular evaluations (including those related to circulating volume changes and manipulations), operationally relevant procedures will be developed to rule out a number of mission-impacting medical conditions. Space-adapted and non-invasive methodologies to study peripheral and central hemodynamics are a valid contribution of this investigation that can later be used to evaluate other countermeasures, as well as to diagnose or rule out arterial, venous, and cardiac pathology. The effect of prolonged weightlessness on venous capacitance or venous blood flow has not been effectively studied using ultrasound, and the protocols developed by this investigation could be used by other investigators for such purposes.

The data gathering techniques for the volume status evaluation will be validated through assessment of Braslet-M application/release effects, and the use of ultrasound will provide hitherto unobtainable data on the overall effects of Braslet-M as a countermeasure. This investigation will provide pilot data regarding the effect of occlusion cuffs on the cardiovascular system of long-duration crewmembers and reveal whether it can be used as a means of acute or chronic volume manipulation for medical purposes. This activity will also determine the on-orbit and ground resources needed to enable such research during future ISS increments until a full-scale evaluation of the Braslet-M device can be performed. This future work would specifically examine the Braslet-M effects on cardiovascular system physiology, its safety, utility, and potentially new or expanded uses. The results of the current, limited investigation will be used to optimize the pre-flight and in-flight training modules for subsequent expedition crews. The lessons learned from this investigation will be used to propose a more formal operationally relevant investigative protocol for future increments, which in turn will address the question regarding utility of Braslet-M for ISS and exploration-class missions.

Space Applications
This SDTO will provide refinements in remote guidance techniques which will allow detailed ultrasound exams to be performed in space with remote guidance by technicians and physicians on the ground. This will enhance the diagnostic and research capabilities of the ISS ultrasound. Data will also be collected regarding the utility and potentially expanded uses of the Braslet-M device for both ISS and exploration class missions. A more detailed understanding of the cardiovascular response to microgravity-induced fluid shifts will also be gained from this work.

Earth Applications
Refinements in remote guidance techniques provided by Braslet will similarly allow detailed ultrasound exams to be performed in terrestrial locations remote from experienced ultrasound technicians and physicians. Examples include rural clinics, disaster areas, and military applications. Additionally, during this SDTO data will be collected regarding the physiological responses to altered circulatory volume distribution which may lend insight to the diagnosis and treatment of terrestrial conditions (such as cardiovascular disease) which result in altered fluid status.

Operational Requirements
A total of five subjects with two scans each have been requested for this SDTO. Subjects are eligible if they are long term residents of ISS, but must be on board at least two weeks to ensure that they have become fully adapted to microgravity from a fluid distribution standpoint. Subjects must also have not exercised, eaten large meals, or worn the Braslet device in the period immediately preceding the scanning session. Ideally, one scanning session per subject is near the beginning of the mission, while the second is near the end of their stay on ISS. Each scanning session is expected to last 1 hour, not including ultrasound deployment and stowage, which is expected to take an additional 1 hour and 20 minutes (per deployment). Data will be recorded in mission control in real time, and additional high resolution images will be downliked following the scanning sessions. The ultrasound and the Braslet devices are available onboard, so no upmass is required, and no hardware or sample return is required.

Operational Protocols
The ISS ultrasound will be deployed and activated. One ISS crewmember per mission will serve as the ultrasound operator and will be remotely guided to scan a subject (self scanning is also included). Detailed ultrasound scans will be taken of the heart, jugular vein (neck), and femoral vein (leg). Parameters include baseline (control), with Braslet-M applied, and with respiratory maneuvers (Valsalva, Mueller). The real time ultrasound video image and cabin video will be privatized and displayed to the experiment team in mission control. Data will be recorded and stored on the ground during the scanning session, and selected higher resolution images will be downlinked from the ISS ultrasound following the experiment. Complete analysis of the ultrasound measurements will be performed following the scanning session.

In the early phases of microgravity adaptation, ISS crewmembers are affected by facial puffiness, nasal stuffiness, painful eye movement, vestibular disorders (dizziness, nausea, vomiting), and the effects of blood shifting towards the head. Over time, ISS crewmembers adjust to the new conditions that microgravity creates. Russian cosmonauts practice a philosophy of microgravity adaptation and have worn the Braslet-M during the early phases of their flight to counter negative effects as they adapt to living and working in microgravity. The Braslet-M is a set of two thigh compression cuffs worn on the upper thigh. The cuffs are tightened to a setting that retains blood in the lower extremities, which mimics the pooling of blood in the legs that is normal on Earth.

The Braslet experiment was performed on nine ISS crewmembers (Expeditions 16 - 20) in 15 experimental sessions to test the device's effectiveness microgravity. Twenty-seven (27) cardiac and vascular parameters were obtained by ultrasound before and during Braslet-M application, and accompanied by breathing maneuvers (Hamilton et al. 2012). Crewmembers used a drinking straw to perform the breathing maneuvers. Valsalva (blowing out against the straw) and Mueller (sucking inward) maneuvers briefly altered pressure in the chest and further revealed the effects of the Braslet-M. Tissue Doppler (TD) imaging was used for the first time in this investigation and served as an excellent tool to assess movement of the heart muscle in different phases of contraction and filling. The experiment also studied leg arteries and veins with and without the Braslet device, and demonstrated that Braslet does indeed retain additional blood into the lower extremities after only 10 minutes of application. Data analysis indicates that there are significant changes generated by the use of Braslet coupled with breathing manipulations, such as the Mueller maneuver. The presence of Braslet-M makes the response to this maneuver more like the response in normal gravity. Thus, even short-term use of Braslet-M in the early adaptation period appears to be physiologically sound with an effect within the first 10 minutes.

A significant proportion of crewmembers require new or adjusted vision correction on orbit, and vision change may persist for months after return. In some crewmembers, vision changes are accompanied by signs of increased pressure within the head, likely associated with the chronic fluid shift. The results of Braslet-M experiment suggest that thigh cuffs could possibly play a role in diminish this fluid shift; however, longer-term application of the cuffs and intermitted use throughout the mission is not well studied. According to the results, the Braslet-M device could also likely be an effective means of treatment for some medical emergencies, such as fluid buildup in the lungs, pulmonary edema (Hamilton et al. 2012).

This investigation is the first report of measurements of the effect of occlusion cuffs on the cardiovascular system on long-duration ISS crewmembers, and results suggest that they may be useful for acute and chronic volume manipulation for both ground and on orbit medical purposes. The safety of extended use (hours) of Braslet-M cuffs are still unknown, although proper calibration and use of specific criteria may allow safe extended use. Many Russian cosmonauts have used Braslet-M for longer periods with no reported complications (Bogomolov et al. 2008). It is expected that elements of methodology developed and validated during this experiment will contribute to planning and support of exploratory missions beyond low Earth orbit. This activity will also aid in defining the resources for comprehensive cardiovascular research during future ISS increments.